Visible Spectral Changes Research Articles

Preparation of ultra-sensitive and selective hydrogen peroxide-based colorimetric sensor using highly exfoliated g-C3N4 nanosheets with peroxidase-like activity.

Ahighly sensitive, portable, rapid, and accurate colorimetricsensing method is presented.It isbased upon exfoliated g-C3N4 nanosheets (E-g-C3N4 NSs), having peroxidase nanozyme-like properties. The as-prepared catalyst (E-g-C3N4 NSs) tends to oxidize the colorless tetramethyl-benzidine (TMB) into oxidized-TMB in the presence of hydrogen peroxide (H2O2) generating adark blue color and corresponding ultraviolet visible-spectral changes following aMichaelis-Menten kinetic. The prepared colorimetric sensor exhibited response within the range 0.001-0.450μM having R2 value of 0.999 and adetective limit (LOD) of 0.15 ± 0.04nM. Furthermore, the sensor also displayed outstanding selectivity, ample stability (10weeks), and excellent practicability in real sample applications. All these outstanding properties were highly attributed to the large surface area with exposed actives sites, high surface energy, and large conductive structure of E-g-C3N4 NSs. For comparison of thecatalytic study, we have also explored the sensing mechanism of B-g-C3N4, using thesame optimized experimental conditions. Resultantly, we concluded that the proposed sensor (E-g-C3N4 NSs) will gain considerable attention for on-site environmental and health monitoring in future endeavor.

An azine‐based halochromic molecular chameleon

An azine‐based halochromic molecular chameleon

A highly sensitive colorimetric and fluorometric sensor for the detection of cyanide

A highly sensitive colorimetric and fluorometric sensor for the detection of cyanide

Development of a novel sensory material for rapid detection of mercury ions in various water sources: Solution and solid-state analysis

Development of a novel sensory material for rapid detection of mercury ions in various water sources: Solution and solid-state analysis

Discovery of a strong rotation of the X-ray polarization angle in the galactic burster GX 13+1

Weakly magnetized neutron stars in X-ray binaries show a complex phenomenology with several spectral components that can be associated with the accretion disk, the boundary, and/or a spreading layer, a corona, and a wind. Spectroscopic information alone, however, is not enough to distinguish these components. The analysis of the timing data revealed that most of the variability, and in particular, kilohertz quasi-period oscillations, are associated with the high-energy component that corresponds to the boundary and/or spreading layer. Additional information about the nature of the spectral components, and in particular, about the geometry of the emission region, can be provided by X-ray polarimetry. One of the objects of the class, a bright, persistent, and rather peculiar galactic Type I X-ray burster was observed with the Imaging X-ray Polarimetry Explorer (IXPE) and the X-ray Multi-Mirror Mission Newton ( Using the data, we obtained the best-fit values for the continuum spectral parameters and detected strong absorption lines associated with the accretion disk wind. IXPE data showed the source to be significantly polarized in the 2--8 keV energy band, with an overall polarization degree (PD) of $1.4<!PCT!> at a polarization angle (PA) of $-2 (errors at the 68<!PCT!> confidence level). During the two-day long observation, we detected rotation of the PA by about 70 with the corresponding changes in the PD from 2<!PCT!> to nondetectable and then up to 5<!PCT!>. These variations in polarization properties are not accompanied by visible spectral state changes of the source. The energy-resolved polarimetric analysis showed a significant change in polarization, from being strongly dependent on energy at the beginning of the observation to being almost constant with energy in the later parts of the observation. As a possible interpretation, we suggest a constant polarization component, strong wind scattering, or a different polarization of the two main spectral components with an individually peculiar behavior. The rotation of the PA suggests a misalignment of the neutron star spin from the orbital axis.

Synthesis, characterization, solvatochromic, computational and antibacterial studies of a series of new 4-imino-3-(2-heteroarylhydrazono)chroman-2-one dyes

Synthesis, characterization, solvatochromic, computational and antibacterial studies of a series of new 4-imino-3-(2-heteroarylhydrazono)chroman-2-one dyes

A selective chromo-fluorogenic chemosensor for visual detection of solution and vapor phase of sarin, tabun mimics diethyl chlorophosphate, diethyl cyanophosphonate

A selective chromo-fluorogenic chemosensor for visual detection of solution and vapor phase of sarin, tabun mimics diethyl chlorophosphate, diethyl cyanophosphonate

UV–visible spectral changes of gamma irradiated olive leaves extract

UV–visible spectral changes of gamma irradiated olive leaves extract

Rational design and construction of S-scheme CeO2/AgCl heterojunction with enhanced photocatalytic performance for tetracycline degradation

Rational design and construction of S-scheme CeO2/AgCl heterojunction with enhanced photocatalytic performance for tetracycline degradation

Chromogenic, specific cascade detection of fluoride and alkaline earth metal ions

Chromogenic, specific cascade detection of fluoride and alkaline earth metal ions

Combined calorimetric, spectroscopic and microscopic investigation on the inclusion complex from cyclocurcumin and sulfobutylether-β-cyclodextrin in aqueous solution and Kinetics of thermal cis-trans isomerization

The complexation reaction between cyclocurcumin (CyCur), a natural curcuminoid with bioactive effects, and sulfobutylether-β-cyclodextrin (SBE-βCD), one of the more versatile and tolerate β-cyclodextrin derivates, was investigated in aqueous solution at 298 K. The UV–vis spectral changes of CyCur in the presence of SBE-βCD indicate the formation of the host-guest inclusion complex according to a 1:1 stoichiometry. The binding constant (Kb) determined by applying the Benesi-Hildebrand model was comparable to the value obtained by Isothermal Titration Calorimetry (ITC) measurements. Moreover, the thermodynamic parameters of the SBE-βCD/CyCur interactions demonstrate that the complexation process is enthalpically driven. Interestingly, microscopy analysis highlights the tendency of cyclocurcumin to aggregate into spherical fluorescent structures able to change their aspect and morphology in the presence of SBE-βCD. Finally, the thermal cis-trans isomerization rates of CyCur in the temperature range 294–314 K and the energetic parameters calculated by Arrhenius and Eyring plots were spectroscopically determined in SBE-βCD aqueous solution.

Colorimetric detection of phosphate-based on iron complexing catechol-displacement assay in eutrophicated water bodies

Colorimetric detection of phosphate-based on iron complexing catechol-displacement assay in eutrophicated water bodies

Photochemical Nitric Oxide Release from S‐Nitrosothiol‐Functionalized Chitosan

AbstractS‐nitrosothiols (RSNOs) are nitric oxide (NO) donor molecules with potential biomedical applications since they mimic NO biological functions, such as vasodilation and inflammatory process regulation. In this work, chitosan (CS), a natural biopolymer widely used as a biomaterial, is functionalized with thioglycolic acid (TGA) or mercaptosuccinic acid (MSA) in reactions mediated by a carbodiimide, yielding CS with thiol contents of 88 µmol g–1 (CS‐TGA) and 126 µmol g–1 (CS‐MSA). The subsequent S‐nitrosation of CS‐TGA and CS‐MSA generates the corresponding S‐nitroso derivatives, CS‐TGA(SNO) and CS‐MSA(SNO). The UV–Vis spectral changes associated with the S‐NO bond cleavage of CS‐TGA(SNO) and CS‐MSA(SNO), monitored in solution over 18 days of storage in a common refrigerator, reveal that these S‐nitroso CS derivatives display enhanced thermal stability in the dark, with half‐life values of 36.1 for CS‐TGA(SNO) and 16.1 days for CS‐MSA(SNO). Conversely, CS‐TGA(SNO) and CS‐MSA(SNO) can release NO photochemically on‐demand under visible light irradiation in a first‐order process triggered by photon absorption that leads to a half‐life of 33 min for both S‐nitroso CS. These results show that CS‐TGA(SNO) and CS‐MSA(SNO) may emerge as new CS‐based biomaterials for providing light‐triggered local NO release in biomedical applications.

A Coumarin151 derived ratiomteric and turn on chemosensor for rapid detection of sarin surrogate

A Coumarin151 derived ratiomteric and turn on chemosensor for rapid detection of sarin surrogate

Multispectroscopic and computational evaluation of the binding of flavonoids with bovine serum albumin in the presence of Cu2+

Multispectroscopic and computational evaluation of the binding of flavonoids with bovine serum albumin in the presence of Cu2+

Colorimetric “off–on” fluorescent probe for selective detection of toxic Hg2+ based on rhodamine and its application for in-vivo bioimaging

Colorimetric “off–on” fluorescent probe for selective detection of toxic Hg2+ based on rhodamine and its application for in-vivo bioimaging

Triazine and Porphyrin-Based Cross-Linked Conjugated Polymers: Protonation-Assisted Dissolution and Thermoelectric Properties

As two pivotal functional segments, triazine and porphyrin can be coupled to form a highly cross-linked conjugated polymer. Although the obtained conjugated polymers are almost insoluble in most so...

Secondary organic aerosol formation from 3C⁎-initiated oxidation of 4-ethylguaiacol in atmospheric aqueous-phase

Secondary organic aerosol formation from 3C⁎-initiated oxidation of 4-ethylguaiacol in atmospheric aqueous-phase

Tuning of renewable biomass lignin into high value-added product: Development of light resistant azo-lignin colorant for coating application

Tuning of renewable biomass lignin into high value-added product: Development of light resistant azo-lignin colorant for coating application

Aqueous-phase oxidation of three phenolic compounds by hydroxyl radical: Insight into secondary organic aerosol formation yields, mechanisms, products and optical properties

Aqueous-phase oxidation of three phenolic compounds by hydroxyl radical: Insight into secondary organic aerosol formation yields, mechanisms, products and optical properties